Recently, in the field of mobile phones, markets for third-generation mobile phones of a wideband-code division multiple access (W-CDMA) system in addition to a global system for mobile communications (GSM) (registered trademark) system have rapidly grown. The W-CDMA system is a frequency division duplex (FDD) communication system in which a frequency band is divided into a frequency band for a transmission signal and a frequency band for a reception signal to simultaneously perform transmission and reception, unlike the GSM system. A signal path through which signals of different frequencies are simultaneously transmitted has a problem in that a signal (intermodulation distortion (IMD)) combined by addition or subtraction of harmonic components and fundamental components of the signals is generated to interfere with the main signals. For example, in an antenna switch used in a mobile terminal performing communications in an FDD system such as W-CDMA, there is a serious problem in that since a reception signal has a power level lower than a transmission signal, the intermodulation distortion serves as radio interference with a reception band to lower reception sensitivity. Therefore, the intermodulation distortion in an antenna switch is considered as an important characteristic along with high-order harmonic distortion (HD).
An antenna switch according to the related art is disclosed in Patent Document 1. In an antenna switch MMIC illustrated in FIG. 2 of Patent Document 1, a high-frequency switch is installed between a terminal connected to an antenna and a terminal receiving a transmission signal and between the terminal connected to the antenna and a terminal receiving a reception signal. The high-frequency switch is embodied by forming high electron mobility transistors (HEMTs) as a multi-gate transistor (such as dual-gate FET, triple-gate FET), and the gates of the transistors constituting the multi-gate are supplied with a control signal for controlling ON and OFF states of the HEMTs via a gate-control resistor. The gate-control resistor includes plural gate resistors connected to the gates of the transistors, respectively, and a coupling resistor for coupling and connecting the gate resistors to a control line through which the control signal is supplied.